Re: air speed measurement above mach 1

Raul Ferreira <1@xxxxx> wrote:
> >> For instance, the sonic boom, it happens when the plane reaches sound
> >> speed. I was told that it happens because the pressure of the air
> >> against the fuselage is "converted" into sound ( correct me if i
> >> wrong). This sound has a frequency or it is just a sudden change in
> >> pressure?
> >
> >You are wrong.

> Why i am wrong? For someone hear something there must be some
> variation in the air pressure at a certain frequency.




> >
> >http://science.howstuffworks.com/question73.htm
> >
> >You might want to spend some time on this site.

> Thank you for your link. And it is more clear to me in terms of waves
> and wake.


> So the wake is formed only by the plane jet noise "trapped" in a
> single bigger wave? The pressure of air in the fuselage doesn't count?

> Quote from that link
> "When an airplane travels through the air, it produces sound waves."

> This seems to me that it is refering to the sound produced by
> variations in air pressure into the fuselage. Or it is just from the
> plane jet engine?


> I had an ideia. This summer holidays i am going to pick up my
> electrodynamic microphone and record some planenoise traveling above
> the sound speed. With an osciloscope and spectrum analyser i might
> have an ideia of the variations of air pressure of a sonic boom.

If you had bothered to actually read the links I provided you would
know that a "sonic boom" is analogous to the wake of a boat.

Engine noise has nothing to do with it.

Everything moving through the air makes noise.

Read the links.

--
Jim Pennino

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